diy solar

diy solar

Simple voltage regulator as controller for small project?

Swing

New Member
Joined
Feb 22, 2022
Messages
136
Hi all,

I built a lot of systems already with the usual charge controllers and inverters etc, but this time a tiny project with a tiny solar panel.

Some LiFePo4 cells, probably at 12v/4s max 20Ah and a 20 to 30W solar panel so very low C rate. Perhaps I will use 2 of these 20W trickle charge solar panels in parallel.
Since it will all be incorporated in a small housing (no ventilation), I was thinking about simplifying the charge controller bit.

What if I were to use a step down voltage regulator/converter?
Somthing like this: https://www.ebay.com/itm/352665799993?hash=item521c850d39:g:AbsAAOSwLBlc3SE6

It is CC current controlled (adjustable) and it has thermal shutdown. Since it is only step down, it means the solar panel voltage needs to surpass my charge voltage level for it to start. By configuring the output current you could change the load on the solar panel. Of course any MPPT regulator does this continuously.
But with such a simple PCB, you could purposefully configure a lower Amp output than the solar panel can put out, so for example only configure 1 Amp (~14W) for a 20 or 25W solar panel. That way it will work in a lot of conditions. And in other conditions it will just stall, but yeah I wanted a cheap simple solution, so that is okay for me.

So of course any real solar controller would outperform this pcb easily, but this would save a lot of space and still work when it is in bright sun.
And I can encapsulate into the packaging.

I know you can buy really cheap low power solar charge controllers, but they don't allow you to configure the voltage, and I doubt if many have a thermal shutdown.

Any thoughts?
 
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